Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
  • H04B5/40—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by components specially adapted for near-field transmission
  • H04B5/48—Transceivers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
  • Y02D30/00—Reducing energy consumption in communication networks
  • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

• the present embodiments relate generally to near-field
• NFC non-media communications
• NFC technology allows for simplified wireless data exchanges between two NFC-enabled devices over a range of several centimeters or less.
• NFC/RFID tag may exchange data with an NFC reader (e.g., in a point-of-sale terminal or another mobile device), thereby allowing a customer to purchase goods or services without exchanging hard currency or physically swiping a credit card.
• NFC technology may also be used to facilitate social networking, contact sharing, and/or establishing other wireless connections (e.g., Bluetooth or WiFi).
• NFC standards include ISO/IEC 18092 and ECMA-340 standards, which define modulation schemes, encoding and decoding schemes, transfer rates, frame format, transmission protocols, and so forth, for an NFC connection. More specifically, to initiate an NFC connection with the target device, the initiator device transmits an un-modulated radio frequency (RF) carrier signal for an active RF guard time (currently set to approximately 5 ms), and then modulates the carrier signal to embed a polling command (e.g., request frame) that requests either an active communication mode or a passive communication mode.
• RF radio frequency
• the initiator device If the initiator device requests the active communication mode, the initiator device terminates transmission of its carrier signal after transmitting the polling command, and then the target device transmits data to the initiator device by generating and modulating its own RF carrier signal. Conversely, if the initiator device requests the passive communication mode, the initiator device continues transmitting its carrier signal, and the target device transmits data to the initiator device by load modulating the initiator device's carrier signal.
• the active communication mode power consumption is shared between the initiator device and the target device, while for the passive communication mode, the target device consumes very little (if any) power because it does not generate its own carrier signal.
• the target device when the initiator device requests the active communication mode in its polling command, the target device is to generate and transmit its own carrier signal no later than a predetermined response time after the initiator device terminates its carrier signal transmission.
• the predetermined response time for active mode communications which is sometimes referred to as the active delay time (T A DT)
• T A DT the active delay time
• the initiator device typically terminates its carrier signal immediately after transmitting the polling command to the target device, for example, so that the initiator device can receive data transmitted from the target device via the target device's own carrier signal.
• the target device typically enables its clock generator immediately after detecting the initial un-modulated carrier signal transmitted from the initiator device and/or generates its own carrier signal only after determining that the initiator device has terminated its carrier signal. In this manner, the target device may have sufficient time to enable its clock generator, stabilize its clock signal, and transmit its own carrier signal within the active delay time (T A DT)- However, if the target device enables its clock generator prematurely or unnecessarily, power consumption may be unnecessarily consumed. For example, if the initiator device subsequently requests the passive
• the target device does not need to generate and transmit its own carrier signal.
• This unnecessary power consumption is of particular concern when the target device is a mobile device having a limited power supply (e.g., a smartphone powered by a small battery).
• the initiator device may selectively extend the transmission of its carrier signal by an extended time period when requesting an active mode NFC connection with the target device, thereby allowing the target device additional time to enable its clock generator and/or stabilize the clock signal used to generate and transmit its own carrier signal.
• the target device may selectively enable its clock generator after receiving and decoding the polling command from the initiator device (e.g., rather than automatically enabling its clock generator upon detecting the initial un-modulated carrier signal transmission from the initiator device).
• the initiator device if the initiator device requests an active mode NFC connection, the initiator device continues transmitting its carrier signal for an extended time period after sending the polling command to the target device (e.g., after modulating a request onto the carrier signal).
• the extended time period may be referred to as an active RF extended time.
• the target device enables its clock generator to generate its clock signal and thereafter transmit its own carrier signal to the initiator device.
• the extended time period provided by the initiator device allows the target device sufficient time to stabilize its clock signal and to transmit its own carrier signal within the active mode response time (e.g., 302 ⁇ ).
• the target device does not enable its clock generator and does not generate its own carrier signal, thereby reducing power consumption in the target device.
• the initiator device includes a look-up table to store one or more values indicating the extended time period.
• the initiator device may select a suitable value for the extended time period in response to one or more operating conditions (e.g., interference conditions, an expected distance between the initiator device and the target device, and so on) and/or characteristics of the target device (e.g., type of clock generator, battery type, and so on).
• FIG. 1 is a block diagram of an NFC system that includes two
• NFC-enabled devices in accordance with some embodiments.
• FIG. 2 is a block diagram of an NFC device in accordance with some embodiments.
• FIG. 3 is an exemplary timing diagram depicting NFC signal transmissions between an initiator device and a target device, in accordance with some embodiments.
• FIG. 4A is an illustrative flow chart depicting an exemplary operation for an NFC device operating as an initiator device in accordance with some embodiments.
• FIG. 4B is an illustrative flow chart depicting an exemplary operation for an NFC device operating as a target device in accordance with some embodiments.
• NFC near field communication
• NFC refers to various communications governed by various NFC protocols including, for example, ISO/IEC 18092, ECMA-340, and/or standards defined by the NFC Forum.
• NFC clock generator refers to a clock generator that generates a clock signal to be used for generating, transmitting, and/or modulating an NFC carrier signal for exchanging data during an NFC connection.
• initiator device refers to an
• NFC-enabled device that initiates an NFC connection (e.g., by transmitting a polling command to another NFC-enabled device), and the term "target device” refers to an NFC-enabled device that responds to a request from the initiator device (e.g., either by transmitting its own carrier signal in response to a request for an active mode NFC connection or by load modulating the initiator device's carrier signal in response to a request for a passive mode NFC connection).
• target device refers to an NFC-enabled device that responds to a request from the initiator device (e.g., either by transmitting its own carrier signal in response to a request for an active mode NFC connection or by load modulating the initiator device's carrier signal in response to a request for a passive mode NFC connection).
• FIG. 1 shows an NFC system 100 that includes two NFC-enabled devices D1 and D2 in accordance with some embodiments.
• NFC devices D1 and D2 are each equipped with an NFC antenna 1 10 capable of exchanging wireless communication signals in the near field with other NFC antennas in other NFC devices.
• the antennas 1 10 of the NFC devices D1 and D2 are brought near each other (e.g., within a few centimeters of each other), they become inductively coupled; once inductively coupled, they allow the NFC devices D1 and D2 to perform near-field communication with each other.
• the antennas 1 10 are loop antennas that allow for radio frequency (RF) transmission and reception, although other well-known antennas can be used.
• RF radio frequency
• near-field communication between the NFC devices D1 and D2 is performed in accordance with one or more standards (e.g., ISO/IEC 18092, ECMA-340, and/or standards defined by the NFC Forum).
• NFC devices D1 and D2 may be any suitable devices that can communicate with each other wirelessly according to NFC protocols or standards.
• both NFC devices D1 and D2 are mobile devices (e.g., cellular phones, personal digital assistants, or other mobile devices).
• NFC device D1 is a mobile device and NFC device D2 is an NFC tag (e.g., a passive radio-frequency identification (RFID) tag).
• NFC device D1 is an NFC reader situated, for example, in a kiosk or admissions gate, and NFC device D2 is a mobile device or NFC tag.
• NFC device D1 is a proximity coupling device (PCD) and NFC device D2 is a proximity integrated circuit card (PICC) (e.g., a contactless smart card).
• PCD proximity coupling device
• PICC proximity integrated circuit card
• NFC device D1 is designated as the initiator device
• NFC device D2 is designated as the target device (as depicted in FIG. 1 ).
• NFC device D1 may operate as the target device
• NFC device D2 may operate as the initiator device.
• FIG. 2 shows an NFC device 200 that is one embodiment of NFC device D1 and/or NFC device D2 of FIG. 1 .
• NFC device 200 includes a well- known receiver/transmitter circuit 210, a processor 220, an NFC clock generator 230, and a memory 240.
• the receiver/transmitter circuit 210 which is coupled to antenna 1 10, to processor 220, and to NFC clock generator 230, may be used to transmit signals to and receive signals from another NFC- enabled device. More specifically, receiver/transmitter circuit 210 receives a clock signal CLK from NFC clock generator 230, and exchanges data and control signals (CTRL) with processor 220. In operation, receiver/transmitter circuit 210 may be used to generate and/or modulate data onto a carrier signal to be transmitted to another device via antenna 1 10, and may be used to receive and demodulate data from a carrier signal received by antenna 1 10. For some embodiments, receiver/transmitter circuit 210 may also be used to load modulate data onto a carrier signal transmitted from another device (e.g., when communicating in the NFC passive mode).
• CTRL data and control signals
• NFC clock generator 230 can be any suitable type of clock generator or clock circuit that generates a clock signal such as CLK suitable for use in generating an NFC carrier signal and/or modulating data onto the NFC carrier signal.
• NFC clock generator 230 may be a voltage- controlled oscillator, a crystal oscillator, or a digital clock generator.
• FIG. 2 depicts NFC clock generator 230 as a dedicated or stand-alone clock generator for providing the clock signal CLK to receiver/transmitter 210, for other embodiments, clock generator 230 may be shared with other resources or modules on NFC device 200.
• NFC clock generator 230 may be implemented within another circuit or module of NFC device 200.
• Memory 240 which is coupled to processor 220, may be any suitable memory element or device.
• Memory 240 may include a look-up table 242 that stores one or more values indicating an extended time period ( ⁇ ⁇ ⁇ ) associated with continuing transmission of the initiator device's NFC carrier signal after a polling command has been modulated onto the carrier signal.
• the extended time period ⁇ ⁇ ⁇ may be predetermined and programmed into table 242 (e.g., by a manufacturer of the initiator device).
• the table 242 may store a plurality of extended time periods TEXT that can be dynamically selected when transmitting a polling command to the target device.
• each of the plurality of extended time periods TEXT may be selected in response to one or more parameters including, for example, current operating conditions, predetermined environmental conditions, the type and/or operating characteristics of the target device's NFC clock generator or battery, and so on.
• Memory 240 may also include a non-transitory computer-readable medium (e.g., one or more nonvolatile memory elements, such as EPROM, EEPROM, Flash memory, a hard drive, and so on) that can store the following software modules:
• a non-transitory computer-readable medium e.g., one or more nonvolatile memory elements, such as EPROM, EEPROM, Flash memory, a hard drive, and so on
• a data exchange software module 244 to facilitate the generation of an NFC carrier signal suitable for NFC data exchanges and/or to modulate data onto the NFC carrier signal (e.g., polling commands, requests, responses, and data to be exchanged with another NFC device) for example, as described for operations 402, 404, 408, 410, and/or 412 of FIG. 4A and operations 452, 454, 458, 462, and/or 464 of FIG. 4B; and
• a power control software module 246 to determine power conditions and/or selectively enable and disable NFC clock generator 230 to reduce power consumption of NFC device 200, for example, as described for operations 457 and/or 460 of FIG. 4B.
• the data exchange software module 244 includes instructions that, when executed by processor 220, can cause NFC device 200 to perform the corresponding functions.
• the power control software module 246 includes instructions that, when executed by processor 220, can cause NFC device 200 to perform the corresponding functions.
• Processor 220 which is coupled to receiver/transmitter circuit
• NFC clock generator 230 can be any suitable processor capable of executing scripts or instructions of one or more software programs stored in NFC device 200 (e.g., within memory 240).
• processor 220 can execute data exchange software module 244 to facilitate the
• Processor 220 can also execute power control software module 246 to determine power conditions and/or selectively enable and disable NFC clock generator 230 to reduce power consumption of NFC device 200. [0027] During the execution of one or more of the software modules stored in memory 240, processor 220 may send data and/or control signals to receiver/transmitter 210, may receive data and/or control signals from receiver/transmitter 210, and may provide a clock enable signal CLK_EN to NFC clock generator 230.
• processor 220 may selectively assert CLK_EN to enable NFC clock generator 230 to generate and stabilize the clock signal CLK in response to determining that a polling command received from another NFC device is requesting an active communication mode, as described in more detail below.
• Processor 220 may also selectively de-assert CLK_EN to disable NFC clock generator 230 from generating the clock signal CLK when the other NFC device is requesting a passive communication mode (e.g., to reduce power consumption).
• NFC device 200 may be used as either the initiator device D1 or the target device D2 in the present embodiments, it is noted that one or more elements of NFC device 200 may be omitted depending upon whether NFC device 200 is used as the initiator device D1 or the target device D2. For one example, when NFC device 200 is used as the initiator device D1 of FIG. 1 , power control software module 246 may be omitted. For another example, when NFC device 200 is used as the target device D2 of FIG. 2, lookup table 242 may be omitted.
• the initiator device D1 may request either an active mode NFC connection or a passive mode NFC connection (e.g., by embedding the request into a polling command modulated onto the initiator device's carrier signal).
• the active mode NFC connection the initiator device D1 and the target device D2 each generate their own carrier signals and transmit data to other device by modulating data onto their own carrier signals (e.g., during alternating time period or slots).
• the target device D2 sends data (e.g., a response to the polling command) to the initiator device by load modulating the initiator device's carrier signal.
• the passive mode NFC connection is suitable for use in environments where the target device D2 has a limited power supply (e.g., when a person uses an NFC-enabled smartphone to purchase goods at a store or restaurant).
• the target device D2 consumes little (if any) power during the passive mode NFC connection is because the target device D2 does not have to enable and operate its own clock generator, and does not have to generate and transmit its own carrier signal.
• the target device D2 when the initiator device D1 requests the active mode NFC connection (e.g., as indicated in the polling command sent to the target device), the target device D2 is to begin
• a conventional NFC target device typically maintains its NFC clock generator in an enabled state in case it needs to generate and transmit its own carrier signal (e.g., for active mode NFC connections) within the 302 ⁇ time period (e.g., as provided by the active delay time T A DT)- Although maintaining the target device's clock generator in an enabled state may result in unnecessary power consumption (e.g., if the initiator device requests the passive mode there is no need for the target device to generate or transmit its own carrier signal), failure to stabilize the target device's NFC carrier signal clock before expiration of the 302 ⁇ S time period may preclude establishing a successful NFC connection.
• power consumption may be reduced in target device D2 by configuring target device D2 to enable its NFC clock generator 230 only in response to receiving a polling command that requests an active mode NFC connection.
• target device D2 does not enable its NFC clock generator 230 or generate its own NFC carrier signal if initiator device D1 requests a passive mode NFC connection, thereby saving power consumption associated with enabling and operating its NFC clock generator 230 and/or transmitter portions of
• target device D2 does not prematurely enable its NFC clock generator 230, thereby further reducing power consumption in target device D2.
• the initiator device D1 may be configured to continue transmitting its carrier signal for an extended time period ( ⁇ ⁇ ⁇ ) after modulating the polling command onto its carrier signal.
• the extended time period ⁇ ⁇ ⁇ may be any suitable value that allows target device D2 sufficient time to enable its NFC clock generator 230 in response to a request for an active mode NFC connection, to stabilize its NFC carrier signal clock, and to transmit its own NFC carrier signal to initiator device D1 .
• target device D2 may wait to enable its NFC clock generator 230 until after decoding the polling command and yet still be able to transmit its own NFC carrier signal back to the initiator device D1 within the 302 ⁇ time period.
• Timing diagram 300 depicts waveforms for initiator device D1 's carrier signal clock CLK_D1 , a first NFC carrier signal CS1 transmitted from initiator device D1 , a second NFC carrier signal CS2 transmitted from target device D2, the clock enable signal CLK_EN in target device D2, and target device D2's carrier signal clock
• initiator device D1 activates its NFC clock generator 230 at time tO.
• the initiator device D1 's carrier signal clock CLK_D1 is stabilized by time t1 , after which initiator device D1 transmits an un-modulated NFC carrier signal CS1 for 5 ms or more.
• initiator device D1 modulates a polling command containing an attribute request frame (ATR_REQ) onto its NFC carrier signal CS1 .
• ATR_REQ attribute request frame
• initiator device D1 after its polling command has been transmitted (e.g., after the last bit of the request frame ATR_REQ is modulated onto carrier signal CS1 ), initiator device D1 continues transmitting its NFC carrier signal CS1 for an extended time period ( ⁇ ⁇ ⁇ ) until time t4.
• conventional initiator devices requesting an active mode NFC connection typically terminate transmission of their carrier signals immediately after transmitting the polling command (e.g., to reduce power consumption and/or to prepare for reception of the target device's NFC carrier signal).
• target device D2 receives the request frame (ATR_REQ) and determines that initiator device D1 is requesting an active mode NFC connection. In response thereto, target device D2 asserts (e.g., to logic high) its clock enable signal CLK_EN to enable its NFC clock generator 230. The target device D2's clock generator 230 warms up by time t5, and just after time t5 stabilizes its NFC carrier signal clock CLK_D2. Thus, after time t5, target device D2's clock signal CLK_D2 becomes available for use by its receiver/transmitter 210 to generate target device D2's NFC carrier signal CS2. Then, at or before time t6, target device D2 transmits its own NFC carrier signal CS2, and at time t7 target device D2 modulates an attribute response frame (ATR_RES) onto its NFC carrier signal CS2.
• ATR_RES attribute response frame
• initiator device D1 terminates its NFC carrier signal CS1 at time t4, which for the present embodiments triggers the beginning of the 302 ⁇ time period during which target device D2 must transmit its own NFC carrier signal CS2 in response to initiator device D1 's request frame. Because target device D2 asserted CLK_EN to enable its NFC clock generator 230 at time t3 (in response to decoding the polling command's request frame), target device D2 is able to stabilize its NFC carrier signal clock CLK_D2 and transmit its own NFC carrier signal CS2 before the expiration of the 302 ⁇ time period at time t6.
• FIGS. 4A and 4B are illustrative flow charts 400 and 450 depicting an exemplary operation for establishing an NFC connection between initiator device D1 and target device D2 in accordance with some embodiments.
• initiator device D1 generates and transmits an unmodulated NFC carrier signal CS1 (402).
• initiator device D1 selects either an active mode or a passive mode NFC connection, and modulates a polling command containing a request for the selected communication mode onto its NFC carrier signal CS1 (404).
• initiator device D1 terminates transmission of its NFC carrier signal CS1 immediately after modulating the polling command onto NFC carrier signal CS1 (408).
• initiator device D1 determines or retrieves the extended time period T E x-r (e.g., from its memory 240) (410), and continues transmitting its NFC carrier signal CS1 for the extended time period ⁇ ⁇ ⁇ after modulating the polling command onto NFC carrier signal CS1 (412).
• target device D2 detects initiator device
• Target device D2 decodes the request frame contained in the polling command and determines whether initiator device D1 is requesting an active mode or passive mode NFC connection (454). If initiator device D1 is requesting the passive mode NFC connection, as tested at 456, then target device D2 de-asserts its clock enable signal CLK_EN to maintain its NFC clock generator 230 in a disabled state (457), and thereafter responds to the polling command by load modulating the initiator device D1 's carrier signal CS1 (458).
• target device D2 enables its NFC clock generator 230 by asserting its clock enable signal CLK_EN (460).
• target device D2 generates its own NFC carrier signal CS2 using the clock signal CLK_D2 provided by its NFC clock generator 230 and transmits the NFC carrier signal CS2 to initiator device D1 (462).
• target device D2 responds to initiator device D1 by modulating a response frame (e.g., ATR_RES) onto its NFC carrier signal CS2 (464).
• a response frame e.g., ATR_RES

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• 2012
  • 2012-10-30 US US13/664,342 patent/US8942628B2/en active Active
  • 2012-10-31 CN CN201280058474.0A patent/CN103959667B/zh not_active Expired - Fee Related
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